Atrophy of the left dorsolateral prefrontal cortex is associated with poor performance in verbal fluency in elderly poststroke women

This study aimed to investigate the association between atrophy in the prefrontal cortex with executive function and verbal fluency in elderly male and female patients poststroke. Thirty elderly female patients with non-aphasic ischemic stroke aged -〉 60 years and 30 age-matched non-aphasic male patients with ischemic stroke were recruited. Automatic magnetic resonance imaging segmentation was used to assess the volume of the whole prefrontal cortex, along with its subdivisions： anterior cingulate cortex, orbitofrontal cortex and dorsolateral prefrontal cortex. The Semantic Verbal Fluency Test was administered at 3 and 15 months poststroke. At 3 months poststroke, left dorsolateral prefrontal cortex volume was significantly correlated with Verbal Fluency Test score in female patients only （partial coefficient = 0.453, P = 0.045）, after controlling for age, education, diabetes, neurological deficit, white matter lesions volume, as well as the location and volume of infarcts. At 15 months poststroke, there remained a significant association between the left dorsolateral prefrontal cortex volume and Verbal Fluency Test （partial coefficient = 0.661, P = 0.001） and between the left prefrontal cortex volume and Verbal Fluency Test （partial coefficient = 0.573, P = 0.004） in female patients after the same adjustments. These findings indicate that atrophy of the left dorsolateral prefrontal cortex contributes to the impairment of verbal fluency in elderly female patients with stroke. Sex differences may be present in the neuropsychological mechanisms of verbal fluency impairment in patients with stroke.

Clustering and switching during a semantic verbal fluency test contribute to differential diagnosis of cognitive impairment

The verbal fluency test （VFT） can be dissociated into ＂clustering＂ （generating words within subcategories） and ＂switching＂ （shifting between clusters）, which may be valuable in differential diagnosis. In the current study, we investigated the validity of VFT in the differential diagnosis of Alzheimer＇s disease （AD, n = 65）, vascular dementia （VaD, n = 65）, mild cognitive impairment （MCI, n = 92）, and vascular cognitive impairment without dementia （VCIND, n = 76） relative to cognitively normal senior controls （NC, n = 374）. We found that in the NC group, the total correct score was significantly correlated with age and education; males generated more subcategories; cluster size increased with education, and subcategory and switching decreased with age. A significantly progressive advantage was observed in VFT scores in the sequence NC 〉 MCI/VCIND 〉 AD/VaD, and this significantly discriminated dementia patients from the other groups. AD patients performed better in all four VFT scores than VaD patients. Subcategory and switching scores significantly distinguished AD from VaD patients （AD 〉 VaD; mean difference, 0.50 for subcategory, P 〈0.05; 0.71 for switching, P 〈0.05）. MCI patients scored higher than VCIND patients, but the difference did not reach statistical significance. These results suggest that semantic VFT is useful for the detection of MCI and VCIND, and in the differential diagnosis of cognitive impairment.

The heterogeneity of aging brain： altered functional connectivity in default mode network in older adults during verbal fluency tests

Background Successful aging （SA） and mild cognitive impairment （MCI） are heterogeneous groups of aging.To explore the heterogeneity,the functional connectivity was studied in these populations.Methods The present study utilized functional connectivity magnetic resonance imaging （fcMRI） to investigate default mode network （DMN） in 8 healthy subjects of SA,8 subjects of usual aging （UA）,and 8 MCI patients during verbal fluency tests （VFTs）.Functional connectivity （based seeds） of different groups was analyzed by using statistical test.Results Compared with SA and UA groups,MCI subjects exhibited decreased functional connectivity in the DMN regions,including the inferior parietal Iobule and left angular gyrus （t=3.53,P 〈0.001）.Compared with UA and MCI groups,the SA elderly exhibited increased functional connectivity in the precuneus （t=3.53,P〈0.001）.Conclusions These findings suggested that abnormalities of functional connectivity in DMN might be related with semantic memory impairment in aging.Left angular gyrus and precuneus might be the potential imaging-based biomarker for distinguishing heterogeneous process of elderly.

Correlation between LIFG and Autonomic Activation during Stressful Tasks:A Functional Near-infrared Spectroscopy (fNIRS) Study

It remains unclear whether language tasks in one＇s first （L1） or second （L2） language can cause stress responses and whether frontal, autonomic and behavioral responses to stressful tasks are correlated. In this study, we studied 22 Chinese subjects whose L2 was English and measured the cerebral blood oxygenation in their frontal lobe by using functional near-infrared spectroscopy （fNIRS） as par- ticipants engaged in a mental arithmetic task （MAT） and verbal fluency tasks （VFTs） in L1 （Chinese） and L2 （English）. To examine the activated cortical areas, we estimated the channel location based on Montreal Neurological Institute （MNI） standard brain space by using a-probabilistic estimation method. We evaluated heart rate （HR） changes to analyze autonomic nervous system （ANS） functioning. We found that the MAT and VFTs induced greater increases in HR than did the control （Ctrl） task. Further- more, subjects developed greater increases in HR in the MAT and VFTt~ than they did in the VFTL1. Compared with the Ctrl task, the MAT and both VFTLland VFTL2 produced robust and widespread bi- lateral activation of the frontal cortex. Interestingly, partial correlation analysis indicated that the activity in the left inferior frontal gyrus （LIFG） [Brodmarm＇s area （BA） 47] was consistently correlated with the increases in HR across the three tasks （MAT, VFTL2, and VFTL1）, after controlling for the performance data. The present results suggested that a VFT in L2 may be more stressful than in L1. The LIFG may affect the activation of the sympathetic system induced by stressful tasks, includin~ MATs and VFTs.

Observation on effect of meridian stimulation on blood oxygenation level of brain by applying Near Infra Red Spectrum(NIRS)

Objective To observe the effect of stimulating Yinttang （印堂 EX-HN 3） and Baihui（百会 GV 20） with electroacupuncture （EA） on blood oxygenation level of brain and explore the feasibility of measuring the therapeutic effect of acupuncture by applying near infra red spectrum （NIRS）. Methods Ten participants semi-randomly selected from 158 adults （random test sequence） were stimulated with EA at the acupoints of EX-HN 3 and GV 20. Verbal fluency task was conducted before and after acupuncture, and changes in blood oxygenation level of cerebral cortex were tested by applying NIRS. Quantitative data were processed with JMP 10.0.2 software, and changes in waveforms of blood oxygenation level of brain before and after treatment were compared by applying NIRS. Results ① The mean of reacting dose （integral value） of blood oxygenation level of cerebral cortex of the 158 adults in the verbal fluency task was 10.6 ± 1.1, and the mean of the whole reacting dose of blood oxygenation level of cerebral cortex at 1/2 period of time during the test （centroids value） was 46.8 ± 1.6. ② In the EA group, the mean of integral value and centroids value of 10 adults were 8.4 ± 5.1 and 54.7± 12.2 before EA while 9.8±3.5 and 41.2±6.7 after EA. The integral value and centroids value of the EA group were closer to the mean of all the subjects. Conclusion It was found by NIRS that the blood oxygenation level of cerebral cortex could be regulated in bi- directional way by stimulating EX-HN 3 and GV 20 with EA, and a further research on whether it directly related to EA is to be made.